The invention relates generally to the field of motorized land vehicles having aerodynamic surface structures, such as foils or wings, used to generate a down force on the vehicle to increase traction or handling characteristics. More particularly, the invention relates to land vehicles known as drag racing vehicles, where the exhaust flow from the engine creates the air passing across the aerodynamic surface structure.
The primary principle of drag racing vehicles is to cover a short distance, usually a quarter mile straight track, from a standing start in less time that an opponent in a parallel lane. This requires quick reaction time by both the driver and the vehicle to most effectively harness the power produced by the engine and transferred through traction generated by the tires. In the early days of drag racing the power available from the engines was limited and the tire industry produced tires of varying widths and tread design that were adequate to provide the required traction on the racing surface. As more powerful engines and better fuels were developed, the engine power was easily capable of causing traction loss, i.e., spinning tires, at the start and at any point on the track. When tires break traction, the acceleration of the car down the track is reduced, which increases the elapsed time for a run. The quest for higher performance led professional racing teams and car builders to develop clutch systems, drive trains and aerodynamic surfaces such as foils or wings in an attempt to harness the enormous power of the newer engines, which are capable of delivering from 3000 to 6000 horsepower from a 500 cubic inch engine, so that tire traction is maintained from the start and through out the race.
The introduction of wings, canards and air foils attached to the dragsters allowed for higher velocities and lower elapsed times, the aerodynamic surface structures creating a down force on the vehicle which increased traction during the race. Current technology provides for a large, three-section, highly cambered, high coefficient of lift wing of no larger than 1500 square inches mounted above the rear tires at a height no higher than 90 inches, with an additional wing mounted forward of the front wheels to offset the pitching moment about the lateral axis of the car caused by inertia and the down force of the rear wing. However, significant aerodynamic down forces are not generated until the vehicle achieves minimum velocities for a given wing design, which is a factor of the camber, surface area, coefficient of lift and other factors. Typically the down forces are not significant until the vehicle surpasses approximately 100 MPH. This means that the wings have no effect at the starting line, so that maintaining traction at the start and through the initial sub-100 MPH portion of the race is dependent on limiting the amount of power transferred to the rear tires by allowing the clutch system to slip until enough down force is generated by the aerodynamic surfaces.
There are additional disadvantages to the typical vehicle design utilizing a large rear wing. The typical design may result in "blow over" if the pitching moment from acceleration and traction exceeds the down force generated by the front wing. The current rules require that the rear wing must be stationary during the race, meaning that the angle of attack cannot be altered to present the optimum down force at a given speed. Thus the wing is positioned at an angle of attack which will generate down force at as slow a speed as possible, allowing more power to be supplied to the rear wheels early in the race. This angular position is more severe than would be required at high speeds and therefore results in excess down force and parasitic drag at high velocities which must be overcome by brute force of the engine. The very shape and size of the wings, along with the supporting and mounting structures, generate undesirable drag. Finally, since the air passing across the wings is ambient air, variations in temperature, altitude and other environmental factors will affect vehicle performance.
It is an object of this invention to provide a more stable dragster by focusing the down force generated by an aerodynamic structure, such as a wing, airfoil or canard, at a point just forward of the rear wheels, thereby creating a negative pitching moment and reducing the possibility of the vehicle blowing over, as well as obviating the need for a front wing. It is a further object to reduce induced and parasitic drag on the vehicle at high speed, to reduce elapsed time by generating a down force on the rear tires immediately upon throttle actuation, thereby increasing traction at the start, to provide for quicker vehicle reaction time through better traction at the start, to allow for a more efficient vehicle with reduced engine power, thereby increasing reliability, and to make irrelevant changes in atmospheric air density, temperature, and velocity in the air stream crossing the aerodynamic surfaces. It is a object to accomplish the above by providing one or more aerodynamic surface structures to create a down force on the rear tires, where the air flow across the aerodynamic surface structures which produces the down force is created by the relatively constant temperature, density and velocity of exhaust gas flow from the engine.